In abiotic degradation the action of light radiation is one of the most important parameters, because polymers undergo degradation due to the action of light (natural or artificial). The aim of this study was to investigate the degradation rate for samples of polypropylene (PP) modified with an organic pro-degradant submitted to ageing in a natural environment and to accelerated ageing test. The degradation behavior of the samples exposed to the ageing processes was evaluated through changes in the degree of crystallinity (Xc ), surface morphology (Scanning Electron Microscopy) and molecular weight. The results indicated that for the modified polypropylene samples natural ageing led to a 42.3% reduction in the molecular weight and the surface morphology showed evidence of erosion. In the accelerated ageing process the UV radiation was stronger, which led to a 94.3% increase in the degree of crystallinity and micro-voids were present on the surface of the modified polypropylene.